It is well understood that viewers and listeners (herein referred to as viewers) generally wish to avoid the annoyance of controlling a device by having to traverse a distance and being in physical contact with the device. The annoyance increases when the viewer is incapacitated, the distance is great, frequent changes must be made, or several devices (e.g. TV, VCR, DVD player, stereo receiver) need to be controlled. This has led to the creation of various remote control methods and mechanisms which allow a viewer to control multiple devices from a resting position.
The first remote control devices were used mainly for military purposes. Radio-controlled motorboats, developed by the German navy, were used to attack enemy ships in World War I. Radio controlled bombs and other remote control weapons were used in World War II. Following World War II, United States scientists developed several nonmilitary uses for the remote control device. Automatic garage door openers became popular in the late 1940's, and the first TV remote control devices were used in the 1950's.
Early in the 1950's, a television remote control device was developed having a long cable attached to the television. Pushing buttons on the remote activated a motor that would rotate the tuner in the television.
Several types of wireless television remote control devices have been developed, including optical, ultrasonic and infra-red controls. In 1955, a remote control device using a flashlight and light receptive sensors was developed. The light receptive sensors were positioned at each of the four corner of the television. The flashlight was shined toward a specific light receptive sensor to control a particular function, such as on, off, volume, and channel tuning. A disadvantage of this remote control device was that people often forgot which corner of the TV operated which control. Also, ambient light, such as sunlight, could erroneously affect control of the television.
Later in the 1950's, ultrasonic television remote control devices were developed. A problem with the ultrasonic television remote control device was that the ultrasonic receptors were sensitive to interference from noise generated by clinking metal. Also, the high frequencies generated by the ultrasonic transmitter were known to cause dogs to bark. The ultrasonic remote was used for approximately two decades until the infrared remote control device was developed.
Modern infra-red remote control devices operate by emitting a respectively different serial stream of infra-red pulses for each control on the remote control device. The remote control device includes an infra-red photodiode that emits the pulses. The receiver typically includes a infra-red phototransistor that receives the pulses. The coded pulse streams are decoded in the receiver, for example, by a microprocessor, to implement the desired functions. Typically, each manufacturer has a distinct set of codes for each different type of device that it sells.
Today, the number of television channels and programs that a viewer may receive at any given time has increased to over several hundred. Conventional analog television systems such as those conforming to the National Television Standards Committee (NTSC) and Phase Alternate Line (PAL) standards transmit one program per 6 MHz or 8 MHz channel. Recently, digital television signal processing techniques have been developed that allow multiple programs to be transmitted in each 6 MHz channel. Furthermore, there are now many sources of television signals. In addition to the conventional broadcast antenna, a viewer may receive television signals via wired cable systems, several different types of satellite systems, so-called wireless cable systems and, in the near future, via a global information network, such as the Internet.
Conventional cable television systems are capable of delivering at least 140 six MHz channels and some systems are capable of delivering over 200 channels via a coaxial cable. Presently, new technology is being implemented to increase the number of programs that can be delivered to the home. This is being done via two technologically strategic moves. The first is to increase the allocated bandwidth to one GHz (which provides for 150, six MHz channels). The second is to use video compression to configure a channel to carry up to ten minor channels in one six MHz wide channel. Channels that include a plurality of minor channels are also known as multiprogram channels. Typical numbers that are used in the industry estimate that about 500 programs can be delivered to the home over a single coaxial cable. Fiber optic cable provides many times the bandwidth of a coaxial cable and promises to be able to provide several thousand programs. In the same way, increased bandwidth for satellite systems may allow a viewer to receive upwards of one thousand six MHz channels, each channel containing up to ten minor channels.
To make matters more complex, a typical home entertainment system includes many devices that may be controlled by an infra-red remote control device. It is not uncommon for a viewer's entertainment center to have a television, a radio receiver an multi-channel amplifier, and a video cassette recorder (VCR). Other common devices include DVD players, CD players, set top boxes, cable converters, satellite receivers, audio tape players, and digital audio tape players (DATs). Each device has several controllable functions, and many of these devices require the viewer to control functions unique to that device (e.g., VCR still frame, programming commands). Often, two or more of these devices are being used concurrently. In a home theatre configuration, for example, a DVD player may be used to provide the video and audio portions of a program. The video portion is displayed on a monitor while the audio portion is played through the amplifier in the viewer's receiver. With the increasing number of devices, the increasing number channels, and the increasing number of functions, many remote control devices multiplex functions, for example, the volume controls for the stereo receiver and the television receiver may share a single group of control buttons since it is unlikely that they will be used at the same time. This multiplexing of functions, however, makes the remote control device more confusing to operate.